1. Field
Aspects of the present disclosure relate to a proton conductive inorganic thin film, a method of forming the proton conductive inorganic thin film, and a fuel cell including the proton conductive inorganic thin film.
2. Description of the Related Art
According to types of an electrolyte and fuel used, fuel cells can be classified as polymer electrolyte membrane fuel cells (PEMFCs), direct methanol fuel cells (DMFCs), phosphoric acid fuel cells (PAFCs), molten carbonate fuel cells (MCFCs), or solid oxide fuel cells (SOFCs).
SOFCs are known to be suitable for use in decentralized power supplies, due to their high electrical efficiency and operability with a variety of fuels, including lower purity gaseous fuels. However, for operation at high temperatures, SOFCs need to be formed of a high-priced material durable against high-temperature environments, and it is not easy to rapidly switch from ON to OFF and vice versa. In this sense, SOFCs are not suitable for various applications, such as portable or vehicular power sources. Therefore, research for operating SOFCs at low temperatures is being actively conducted.
PEMFCs operating at 100° C. or higher temperatures in non-humidified conditions, as compared to those operable at low temperatures, do not need a humidifier, and are known to be convenient in terms of control of water supply and highly reliable in terms of system operation. Furthermore, such PEMFCs may become more durable against carbon monoxide (CO) poisoning that may occur with fuel electrodes as they operate at high temperatures, and thus, a simplified reformer may be used therefor. These advantages mean that PEMFCs are increasingly drawing attention for use in such high-temperature, non-humidified systems.
Along with the current trends for lowering the operation temperature of SOFCs and increasing the operation temperature of PEMFCs as described above, fuel cells operable in a moderate temperature range are drawing more attention.
However, electrolyte membranes of fuel cells that have been developed so far do not exhibit satisfactory proton conductivities at moderate temperatures, and thus, still demand further improvement.